Circuit designers are increasingly turning to differential circuitry as a means of enhancing performance in radio circuitry. Differential amplifiers and mixers are an integral part of such circuitry, and are used in such radio applications as direct conversion receivers. For example, a direct conversion receiver may use an amplifier to amplify a received signal prior to signal processing. The amplifier is generally designed to produce a gain in a forward path with little or no reverse leakage. Reverse leakage is an unintended consequence of particular amplifier designs, and can lead to such problems as circuit instability and radio interference.
It is desirable to have a differential amplifier in which reverse transmission is substantially reduced in order to improve circuit stability and to reduce the effects of interference in radio applications. Therefore, a differential amplifier with improved reverse isolation is needed.